1. Field of the Invention
The present invention relates to an automotive internal combustion engine cooling system which can reduce exhaust emissions and improve the fuel economy and the promptness of effective heating, when a water-cooled internal combustion engine (an engine) is started, by causing the temperature of an engine main body or of engine cooling water to be increased sufficiently at an early time after the engine is started.
2. Description of the Related Art
As a cooling system for attempting to promote the warm-up of a water-cooled internal combustion engine (an engine), there has been conventionally proposed a cooling system in which a heat storage tank, which stores cooling water flowing out of the engine while maintaining the temperature of the cooling water, is disposed in a cooling water circuit, whereby hot cooling water stored in the heat storage tank is introduced into the engine to thereby promote the warm-up of the engine.
As one conventional example, there exists an automotive internal combustion engine cooling system which was made known to the public by Japanese Unexamined Patent Publication No. 10-71838. According to this conventional system, while the engine is being warmed up, if the temperature of cooling water flowing out of the heat storage tank provided in the cooling water circuit is below a predetermined temperature (60xc2x0 C.), all the hot cooling water stored in the heat storage tank is understood to have flowed out of the tank, and a cooling water inlet path is closed, whereas a bypass water path is opened, whereby of the cooling water flowing out of the engine, the cooling water whose temperature remains low immediately after the engine is started up, is temporarily stored in the heat storage tank. Thus, the cooling water, whose temperature remains low immediately after the engine is started up, is prevented from circulating within the engine thereby promoting the warming-up of the engine.
With this conventional cooling system, however, in the event that the cooling water flows into the heat storage tank when a heating performance is being required by a heater core (an air conditioner) which is provided in a cooling water circuit of the engine, the flow rate of cooling water (hot water) on a heater core side is reduced, leading to a risk of a problem that the temperature of air, which flows through the heater core to be let out into the passenger compartment, is lowered.
The present invention was made in view of these situations, and an object thereof is to provide an automotive internal combustion engine cooling system in which a heat storage element can secure a sufficient heat storing performance without deteriorating the air conditioning performance of a heater core.
According to the present invention, there is provided an automotive internal combustion engine cooling system in which cooling water for a water-cooled internal combustion engine is designed to be circulated by means of a pump, the automotive internal combustion engine cooling system comprising a cooling water circuit in which cooling water circulates in a radiator adapted to cool cooling water from the internal combustion engine, a hot water circuit in which hot water circulates in a heater core adapted to heat air to be let out into a passenger compartment using hot water from the internal combustion engine as a heat source, an air mixing door for adjusting the volume of air which passes through the heater core, a heat storage element bypass passage for passing hot water into the heater core from the hot water circuit, a heat storage element installed in the heat storage element bypass passage for storing hot water supplied from the internal combustion engine, a flow path selector valve for adjusting the distribution of hot water to the heat storage element and the heater core, and a control unit for controlling the operation of the air mixing door and the flow path selector valve, wherein the control unit controls the flow path selector valve such that the flow rate of hot water to be distributed to the heater core is increased as the volume of air passing through the heater core increases.
In addition, when the volume of air passing through the heater core is equal to or larger than a predetermined value, the control unit controls the flow path selector valve such that the flow rate of hot water to be distributed to the heater core becomes larger than the flow rate of hot water to be distributed to the heat storage element. According to the construction, the drawback inherent in the related art, that when the heating performance is required by the heater core, cooling water flows into the heat storage element, and the flow rate of hot water on the heater core side is reduced, whereby the temperature at air outlets is lowered largely, can be prevented.
Additionally, according to the present invention, there is provided an automotive internal combustion engine cooling system wherein the control unit controls the flow path selector valve such that the flow rate of hot water to be distributed to the heater core becomes zero when there exists almost no air to be distributed to the heater core. According to the construction, an efficient and sufficient heat storage can be secured at the heat storage element.
Furthermore, according to the present invention, there is provided an automotive internal combustion engine cooling system, wherein the control unit has a computing device for computing a required temperature at air outlets temperature (TAO) which is a target temperature of air to be let out into the passenger compartment, and wherein the control unit controls the flow path selector valve such that when the required temperature at air outlets exceeds a predetermined value, the flow rate of hot air to be distributed to the heater core becomes larger than the flow rate of hot water to be distributed to the heat storage element. According to the construction, the required temperature, at the air outlets into the passenger compartment, can be obtained.
Moreover, according to the present invention, there is provided an automotive internal combustion engine cooling system, wherein the control unit controls the flow path selector valve such that when the temperature of hot water located in the vicinity of the heater core is higher than a predetermined value, the flow rate of hot water to be distributed to the heat storage element becomes larger than the flow rate of hot water to be distributed to the heater core. According to the construction, a sufficient heat storing performance can be ensured without deteriorating the air conditioning performance.
In addition, according to the present invention, there is provided an automotive internal combustion engine cooling system, wherein the control unit controls the flow path selector valve such that when the engine speed is lower than a predetermined engine speed, the flow rate of hot water to be distributed to the heater core becomes larger than the flow rate of hot water to be distributed to the heat storage element. According to the construction, the vehicle can secure a sufficient temperature at air outlets even when the vehicle runs at a slow speed.
Additionally, according to the present invention, there is provided an automotive internal combustion engine cooling system, wherein the control unit controls the flow path selector valve such that when the vehicle speed is slower than a predetermined vehicle speed, the flow rate of hot water to be distributed to the heater core becomes larger than the flow rate of hot water to be distributed to the heat storage element. According to this construction, the vehicle can secure a sufficient temperature at the air outlets even when the vehicle runs at a slow speed.
Furthermore, according to the present invention, there is provided an automotive internal combustion engine cooling system, wherein a heat storing electric water pump is provided in the heat storage element bypass passage for passing hot water to the heat storage element, and wherein the control unit controls the heat storing electric water pump such that when the volume of air passing through the heater core is equal to or smaller than a predetermined value, the flow rate of hot water to be distributed to the heat storage element becomes larger than the flow rate of hot water to be distributed to the heater core. According to the construction, a sufficient heat storing performance can be secured without deteriorating the air conditioning performance.
Moreover, according to the present invention, there is provided an automotive internal combustion engine cooling system, wherein an electric water pump for a heater is provided in a passage for passing hot water to the heater core, and wherein the control units controls the electric water pump for a heater such that when the volume of air passing through the heater core is equal to or larger than a predetermined value, the flow rate of hot water to be distributed to the heater core becomes larger than the flow rate of hot water to be distributed to the heat storage element. According to the construction, a sufficient temperature at the air outlets can be ensured.
In addition, that the volume of air is equal to or larger than the predetermined value means that an opening degree of an air mixing door which controls a volume of air passing through the heater core is equal to or larger than a predetermined opening.
The present invention may be more fully understood from the description of preferred embodiments of the invention, as set forth below, together with the accompanying drawings.